Automatic torque calibration for roller shades

ABSTRACT

A method that detects obstacles on a roller shade&#39;s travel that create excess torque by sensing the current draw from a motor and method by which the motor can calibrate itself to detect excess torque. During the roller shade&#39;s travel, it will record the instantaneous torque being generated at various points. For example, it will store the greatest value in the shade motor&#39;s non-volatile memory as the normal operating torque.

BACKGROUND OF THE INVENTION

Technical Field

The present invention generally relates to a system and method for raising and lowering roller shades and more particularly to system and methods to mitigate component damage or user injury during use.

Background Art

One type of motorized window treatment is a motorized roller shade. A typical motorized roller shade includes a flexible shade fabric wound onto an elongated roller tube. The roller tube is rotatably supported so that a lower end of the flexible shade fabric can be raised (i.e., wound) or lowered (i.e., unwound) by rotating the roller tube. The roller tube is rotated by a motorized drive system.

Motorized roller shades can be automated to automatically raise and lower. Unlike manual shades, where the user walks up to the window and opens or closes the shade using a cord or by pulling on the shade, motorized shades make it easy to open or close one or multiple shades with the touch of a button, or by programming them to automatically move at a specific time with no user interaction. In this regard, automation can be used to help minimize heat gain, prevent glare, or protect furnishings from harmful Ultra Violet rays.

Due to the automated nature of movement of motorized window treatments, a user may not realize if there is an obstruction. An obstruction may interfere with the shade and limit its movement. If a shade is lowered and encounters an obstruction, the shade fabric normally will bunch up. Damage normally does not occur to either, the motor nor an occupant of the room during lowering. However, when the shade is raised, the presence of an obstructing object may cause damage to the motor or brackets, for example, and poses an injury risk to the user. The amount damage, in some cases, may be directly related the amount of torque created.

SUMMARY OF THE INVENTION

It is to be understood that both the general and detailed descriptions that follow are exemplary and explanatory only and are not restrictive of the invention.

DISCLOSURE OF INVENTION

The present invention provides a method that detects obstacles that create excess torque by sensing the current draw from a motor. According to a first aspect, the present invention provides a method by which the motor can calibrate itself to detect excess torque. In one embodiment the motor can be calibrated to detect excess torque is to perform a step during the manufacturing process.

According to a second aspect, after the shade is completely manufactured it is finally inspected on a test rack. The shade operates from its lowest limit (fully closed or lowered) to its highest limit (fully open or raised). During the shade's travel, it will record the instantaneous torque being generated at various points. It will store the greatest value in the shade motor's non-volatile memory (NVRAM). This will be considered the normal operating torque.

There are good reasons not to set the greatest value at the factory. First, it does not represent the final installation of the shade. There are a number of things that can change the amount of torque required based on the installation. For example, adding side channels could add friction to the shade, resulting in more torque required to raise it. Mechanical wear over time may vary among shades. Moreover, this approach only takes into consideration fully assembled shades. If we were to send a replacement motor out to be swapped in the field, the normal operating torque value would be invalid because we cannot possibly test the motor in the same exact shade as the customer already has in the field.

According to a third aspect, during normal operation of the shade, any time the shade is sent from its lowest limit to highest limit uninterrupted, the normal operating torque is re-evaluated. This new normal operating torque is compared against the previous value that was stored in NVRAM. If the current torque being generated is exceeds a predetermined factor of the normal operating torque, it is presumed that the shade has become obstructed. In this case, the motor will stop moving and reverse direction a predetermine amount to remove any built up tension in the shade (eg. One-half of a revolution.)

On the other hand, if the torque being generated is less than a predetermined factor of the normal operating torque, then we can assume that this value can be used for the new normal operating torque. The value currently stored in NVRAM is replaced by this new value.

The present invention seeks to overcome or at least ameliorate one or more of several problems, including but not limited to, minimizing damage to a component or injury to a user in the operating roller shades.

Brief Description of Drawings

The accompanying figures further illustrate the present invention. The components in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is an exploded perspective view of an exemplary motorized roller shade according to an embodiment or the present invention.

FIG. 2 shows a partial block diagram of an exemplary controller for the system of FIG. 1.

FIG. 3 shows the steps of an illustrative method of OCTH auto calibration using the system of FIG. 1.

LIST OF REFERENCE NUMBERS FOR THE MAJOR ELEMENTS IN THE DRAWING

The following is a list of the major elements in the drawings in numerical order.

-   100 Motorized Roller Shade Device -   101 Roller Shade Fabric -   104 Drive Unit -   105 Spline Roller -   106 Exposed Hem Bar -   202 Shade Motor -   203 Motor Controller -   204 NVRAM -   205 Interface -   206 Control System -   207 Hall Effect Sensor -   300 OCTH auto calibration method -   301 Wait for lower limit step -   302 Wait for upper limit command -   303 Reach top limit success -   304 Store the new OCTH value -   305 Discard data from run

DETAILED DESCRIPTION OF THE INVENTION Mode(s) for Carrying Out the Invention

The preferred embodiment of the present invention is described herein in the context of roller shades, but is not limited thereto, except as may be set forth expressly in the appended claims.

Disclosed are a system and a method for calibrating and controlling movement of a roller shade according to a detected load that is measured during normal operation. During a roller shade's travel, the instantaneous torque being generated at various points is determined. In one embodiment, the greatest value is stored in a non-volatile memory (NVRAM) of shade motor. Generally, the stored value can be considered the normal operating torque. The store value is periodically updated to compensate for any external factors. External factors may include: temperature, humidity, grease viscosity changes, and/or mechanical component wearing.

Initially, the shade is programmed to have a default OCTH value of zero. With an OCTH value of zero movement will not be interrupted in response to a sensed value of current. Put differently, any driver circuit overload protection would come from, for example, some other hardware protection mechanism engineered into the product.

Referring to FIG. 1, motorized roller shade device 100 may include a roller shade fabric 101, drive unit 104, a spline roller 105, and an exposed hem bar 106.

Referring to FIG. 2, shown is an exemplary controller, according to one embodiment. The controller may include a shade motor 202, a motor controller 203, an interface 205, a control system 206, and a Hall Effect sensor 207. The controller may further include a nonvolatile (NVRAM) memory 204 for storing OCTH values. The control system 206 can be connected via a wired connection using a protocol such as Ethernet, or communicate via wireless communication using IR, or RF circuitry.

Referring now to FIG. 3, shown is an exemplary dynamic OCTH calibration method 300. This method can be used for different shaped and sized shades 101. At step 301, the Motorized Roller Shade Device waits for the roller shade fabric 101 to be at the lowest limit (fully closed or lowered). When the roller shade fabric 101 is at the lowest limit, Motorized Roller Shade Device waits for a command to go to the upper limit, step 302, in which the OCTH auto calibration data capture will begin.

While rising towards the upper limit, if there is no over current event and the shade effectively reaches the top limit (step 303), the data will be valid, and the OCTH auto calibration algorithm will proceed to calculate and store the new OCTH value (step 304). If an over current event was detected, the normal handler of this event will be executed, and the auto calibration algorithm will not use the data from this run (step 303.)

In some embodiments, the lower limit can be changed. In these embodiments, adjustment to the OCTH may be needed, for example to compensate for the new amount of torque required to roll the additional fabric. Accordingly, whenever the lower limit is changed, the present OCTH may be invalidated to Zero and may be recalculated properly on the next bottom to top run.

The risk that the shade might encounter an unexpected obstacle and will not stop the motor until the amount of drawn current is high is very low in comparison to the normal expected every day operation of the shade.

The Auto Calibration of the OCTH may be calculated in various ways. New OCTH values can be determined, for example, as a sum of: a peak value; fixed minimum value; and a percentage of an average. Other ways may include accounting for the weight of unrolled roller shade fabric 101 at any given time.

LIST OF ACRONYMS USED IN THE DETAILED DESCRIPTION OF THE INVENTION

The following is a list of the acronyms used in the specification

-   NVRAM Non-volatile memory -   OCTH Over-Current Threshold -   IR Infrared -   RF Radio Frequency

ALTERNATE EMBODIMENTS

Alternate embodiments may be devised without departing from the spirit or the scope of the invention. 

What is claimed is:
 1. A method for controlling a motorized roller shade device, the device including a roller shade fabric, a drive unit, a spline roller, a hem bar, a shade motor, a motor controller, a Hall Effect sensor, and a nonvolatile memory for storing over-current threshold values (OCTH), the method comprising the steps of: waiting for said roller shade fabric to be at a lowest limit; after said roller shade fabric is at the lowest limit, waiting for a command to go to an upper limit; capturing an over-current threshold value (OCTH) auto calibration by calculating the sum of a peak value, a fixed minimum value, and a percentage of an average value in order to determine a replacement value; storing said over-current threshold value (OCTH) auto calibration if there is no (a) over current event and (b) the shade effectively reaches said upper limit; and discarding said over-current threshold value (OCTH) auto calibration if an over current event was detected, wherein said over current event further causes said shade motor to stop and reverse direction by a predetermined number of revolutions thereby removing any built up tension in said roller shade fabric.
 2. The method of claim 1, wherein said discarding said over-current threshold value (OCTH) auto calibration if an over current event was detected further comprises: setting said over-current threshold value (OCTH) equal to Zero.
 3. The method of claim 1, further comprising the operations of: setting said over-current threshold value (OCTH) equal to Zero whenever said lower limit is changed.
 4. The method of claim 1, wherein said predetermined number of revolutions is at least one-half of a revolution. 